The present invention relates generally to medical graft products that exhibit increased resistance to enzymatic breakdown. One aspect of the present invention provides an extracellular matrix (ECM) material treated with an agent that increases its resistance to digestive enzymes such as pepsin while allowing the ECM to retain beneficial grafting properties.
As further background, extracellular matrix materials, including submucosa, are known medical graft materials. See, e.g., U.S. Pat. Nos. 4,902,508, 4,956,178, 5,281,422, 5,372,821, 5,554,389, 5,993,844, 6,099,567, and 6,206,931. As taught in these patents, submucosa from various biological structures such as small intestine, stomach, and the urinary bladder provide predominantly collagenous materials useful in a variety of surgical procedures where tissue support and/or ingrowth are desired.
U.S. Pat. No. 4,976,733 to Girardot teaches the covalent coupling of aliphatic carboxylic acids having from about eight to about thirty carbon atoms to a prosthesis before implantation in a mammal in order to retard or prevent calcification of the prosthesis. The prosthesis materials disclosed include natural tissue, porcine heart valve tissues, and urinary tract and bladder replacements.
U.S. Pat. No. 5,447,536 to Girardot et al. teaches fixation agents for biological tissue that may include di- or tri-carboxylic acids having about six to about eight carbon atoms. The fixation process creates amide linkages between and within the molecules of the biological tissue thereby producing tissues resistant to calcification. In addition, the resulting tissue is not toxic and does not elicit inflammatory responses after implantation. The prosthesis materials disclosed include natural tissue, porcine heart valve tissues, and urinary tract and bladder replacements.
In view of the above background, there remain needs for improved or alternative medical graft products; especially graft products that are resistant to enzymatic degradation. The present invention is addressed to those needs.